Hemodynamics and Blood-05 Flashcards
blood pressure
the pressure that is exerted by the blood against the walls of blood vessels and measured in mmH, mostly generated by ventricular contraction
pulse pressure (PP)
difference between systolic and diastolic pressure
mean arterial blood pressure
the average pressure during the entire cardiac cycle, mean ABP = diastolic + 1/3(PP); significance is CO x TPR, your BP is a function of how much blood you push out of the heart per min. and how much resistance the heart is working against
what factors affect blood pressure?
cardiac output, blood volume, peripheral vascular resistance
pressure
flow x resistance
flow
pressure/resistance
vascular resistance
friction b/w blood and the vessel walls
factors affecting vascular resistance
blood vessel radius, blood viscosity, blood vessel length
in what ways is blood pressure regulated?
neural, via baro and chemoreceptors, and hormonal, via E and NE, ADH, atrial natriuretic peptide (ANP), renin-angiotensin-aldosterone pathway (RAA)
how is blood pressure regulated in the short-term?
neurally, sometimes hormonally
how is blood pressure regulated in the long-term?
hormonally
how do baroreceptors correct for hypotension?
upon detecting BP decrease, sensory info. travels to medulla oblongata to increase sympathetic outputs by increasing CO (SV & HR) and TPR; message sent to pacemaker cells and heart wall
how do baroreceptors correct for hypertension?
upon detecting BP increase, sensory info. travels to medulla oblongata to increase parasympathetic outputs by decreasing HR, message sent to pacemaker cells
short-term hormonal regulation
activation of sympathetic nervous system releases epinephrine and norepinephrine from the adrenal glands (goes directly into blood and stimulates target organs)
ADH (vasopressin)
release from post. pit. in response to dehydration or decreased blood vol., increases renal water retention and systemic vasoconstriction to increase BP
atrial natriuretic peptide (ANP)
released by atrial cells when they’re stretched out too much, causes vasodilation, promotes renal loss of salt/water and lowers BP
RAA system
regulates BP; low circulating renal blood volume causes renin to be released from kidney which stimulates formation of angiotensin I which converts to angiotensin II to increase BP by vasoconstriction and increased aldosterone production (promotes water reabsorption and secretion of K+ and H+ into urine
shock
the failure of the CV system to deliver enough oxygen and nutrients to meet tissue demand
components of shock
inadequate perfusion or increased demand, cells forced to switch to anaerobic respiration, lactic acid build up, cells and tissues become damaged and die
what are some compensatory mechanisms of shock?
activate RAA system, secrete ADH, activate SNS, release of local vasodilators
heart failure
a chronic condition in which the heart is unable to pump out all of the blood that it receives
what is a major sign of left-sided heart failure?
pulmonary edema (crackles in the lung fields); LV receives blood from the LA which receives blood from the pulmonary veins
what is a major sign of right-sided heart failure?
tissue edema; fluid sits in veins and venules, increases hydrostatic pressure within vessels, therefore more fluid leaking out into tissues
what are the functions of blood?
transportation, regulation and protection
components of blood
plasma and formed elements
what type of tissue is blood?
connective tissue
complete blood count (CBC)
comprehensive blood test that includes red blood cell count (RBC), white blood cell count (WBC), hemoglobin (Hgb), hematocrit (Hct), white blood cell differential, and platelet count + morphology
how to obtain a venous blood sample?
venipuncture with a vacutainer
how to obtain ABG?
arterial stick at the brachail artery
how to obtain a blood sample from the capillaries or to check blood glucose?
finger/heel stick
red blood cells
biconcave disc with greatest SA:V ratio, has strong and flexible membrane, no nucleus, lacks mitochondria, has hemoglobin
hemoglobin
iron-containing protein in red blood cells that carries oxygen for delivery to cells; each can bind 4 O2 molecules, and it also works as a tissue oxygen buffer system
erythropoeisis
formation of RBCs
what occurs if the rate of RBC destruction exceeds the rate of production?
anemia
hemoglobin components
most are recylced; the globular part is broken down into a.a.’s to make new proteins, and the non-protein heme is toxic waste that is discarded (bilirubin), iron is saved to make new hemoglobin
bilirubin
pigment released by the liver in bile; accumulation causes jaundice as a result of liver damage
what happens to RBC count in response to hypoxia?
decreased O2 levels signal erythropoetin release, stimulating the red bone marrow to produce more RBC to increase O2 carrying capacity
what can occur with too much RBCs in the blood?
increased blood viscosity which increases the risk of heart attack and stroke
what factors should be considered in one’s RBC count and O2 levels?
altitude, blood donation, kidney failure, renal artery stenosis
